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MD2 Foundation > Central Nervous Systems Infections > Flashcards

Central Nervous Systems Infections Flashcards

1
Q

What are the different types of central nervous system (CNS) infections?

A 
Meningitis
Encephalitis
Brain abscess
Subdural empyema
Spinal epidural abscess
Vertebral osteomyelitis
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2
Q

What differential diagnoses need to be considered when the patient reports that the headache is their “worst headache ever”?

A

Meningitis

Subarachnoid haemorrhage

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3
Q

Does having no nuchal rigidity rule out meningitis?

A

Nuchal rigidity classically in paediatrics

In adults, presence is worrying, but not having it is common

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4
Q

What are the common causes of acute headache?

A 
Tension-type headache
Migraine
Infections around head
- Sinusitis
- Systemic infections
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5
Q

What are the serious causes of acute headache?

A 
Intracranial infections
- Meningitis
- Encephalitis
- Intracerebral abscess
Intracrainall haemorrhage/mass lesion
Giant cell arteritis
Glaucoma
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6
Q

How can meningitis be categorised?

A

Purulent/acute bacterial meningitis

Aseptic meningitis

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7
Q

What are the causes of aseptic meningitis?

A 
Viral - most common
TB, other bacteria
Fungal
Parameningeal infections
Malignancy
Inflammatory
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8
Q

What are the likely causes of meningitis if the timeline is acute?

A

Acute bacterial

Viral

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9
Q

What are the likely causes of meningitis if the timeline is sub-acute or chronic?

A

TB
Fungal
Malignancy
Inflammatory

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10
Q

What are the clinical features of acute bacterial meningitis?

A 
Headache = primary symptom
- Rapid onset - but not thunderclap
- Patient presents fast - within 24 hours
- Severe
- May be absent in
   - Neonates
   - Elderly
   - Immunosuppressed
Classic triad of additional features
- Fever
- Neck stiffness
- Altered mental state
- Present in <1/2
- Most will have one
Altered mental state usually not primary feature at onset but can be prominent at presentation
Focal neurological signs
- Seizures can occur
Nuchal rigidity can be present on examination
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11
Q

What is the clinical presentation of viral meningitis?

A 
Acute, severe headache
\+/- fever
No
- Hypotension
- Decreased conscious state
- Focal neurological signs
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12
Q

What is the clinical course of viral meningitis?

A

Self-limiting
Improvements within few days
Resolution within 1-2 weeks

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13
Q

What are the investigations for suspected meningitis?

A

Brain CT
- Start empirical treatment before
Lumbar puncture
- To do this safely, need to know they don’t have space occupying lesion

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14
Q

How long can CRP take to raise after sepsis?

A

12-24 hours

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15
Q

What are the parameters for a normal lumbar puncture?

A

Opening pressure = 20 mmHg
- Any higher = raised intracranial pressure
White cell count = 5 cells/um
RBC:WBC ratio - if 1000:1, put your needle through and into peripheral blood (capillaries)
Polymorphs = 0, maybe 1
Glucose = 60-100% of peripheral glucose

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16
Q

What does elevated protein the CSF mean?

A

Inflammation

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17
Q

What does decreased glucose in the CSF mean?

A

Bacteria
Possibly cancer
Fungi
Mycobacteria

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18
Q

What are the parameters of CSF in acute bacterial meningitis?

A 
Appearance = cloudy
WCC >1000 cells/uL
Differential: >95% polymorphs
Protein >1 g/L
Glucose: decreased
19
Q

What are the parameters of CSF in viral meningitis?

A 
Appearance = clear
WCC <500 cells/uL
Differential: lymphocytes
Protein = 0.4-1 g/L
Glucose: normal
20
Q

What are the common causes of bacterial meningitis in neonates?

A

Group B Streptococcus
E coli
Listeria

21
Q

What are the common causes of bacterial meningitis in infants and children?

A

Streptococcus pneumoniae
Nesseria meningitidis
Haemophilus influenzae type b
- Decreased because of vaccine

22
Q

What are the common causes of bacterial meningitis in adolescents and young adults?

A

N meningitidis

S pneumoniae

23
Q

What are the common causes of bacterial meningitis in older adults?

A

S pneumoniae
N meningitidis
Listeria

24
Q

What are the common causes of viral meningitis?

A

Enteroviruses = most common
HSV
VZV
HIV

25
Q

Who is antibiotic prophylaxis important for in bacterial meningitis?

A

Close contacts of cases of N meningitidis and H influenzae, but not S pneumoniae

26
Q

What is the empirical therapy for acute bacterial meningitis?

A 
Dexamethasone + ceftriaxone/cefotaxime
\+ benzylpencillin to cover Listeria if
- Immunocompromised
- Age 50+
- History of hazardous alcohol consumption
- Pregnant
- Debilitated
\+ vancomycin if 
- Gram positive diplococci seen on Gram stain of CSF
- Pneumococcal Ag assay positive
- Suspected otitis media/sinusitis
- Recent treatment with beta lactam
27
Q

What are the possible causes of altered mentation and fever?

A 
Delirium with non-CNS condition
Encephalitis
Meningitis - later in course
Brain abscess
Intracranial tumour/haemorrhage
Seizures
28
Q

What is the treatment for presumed HSV encephalitis?

A

IV acyclovir

29
Q

What is the clinical presentation of encephalitis?

A 
Confusion
Agitation
Decreased conscious state
Focal neurological signs
Seizure
Headache - not primary symptom
Fever - common but not universal
30
Q

What is the most common cause of encephalitis?

31
Q

What are the investigation results for encephalitis?

A 
CSF
- Mild-moderate increase in lymphocytes
- Mild increase protein
- Normal glucose
- HSV PCR sensitive but can be early false negatives
MRI
- Pattern of inflammation
32
Q

What is the presentation of a brain abscess?

A 
Classic triad
- Focal neurological signs
- Fever
- Headache
Often just
- Confusion
- Seizures
- Nausea
More prolonged presentation - weeks
33
Q

What are the possible sources of a brain abscess?

A

Contiguous; eg: sinusitis

Haematogenous; eg: lung abscess

34
Q

What are the possible organisms causing a brain abscess?

A

Oral Strep
Anaerobes
Staphylococcus aureus

35
Q

What is the management of a brain abscess?

A

Drainage + prolonged antibiotics

- Antibiotics only go where there’s blood - centre of abscess doesn’t have blood flow

36
Q

What does S aureus in the urine mean?

A

Result of S aureus bacteraemia until proven otherwise

37
Q

What is the source of vertebral osteomyelitis?

A

Haematogenous seeding

38
Q

What is the source of a spinal epidural abscess?

A 
Contiguous spread; eg: vertebral osteomyelitis
Haematogenous seeding; eg:
- Skin
- Soft tissue
- Urinary
- GI
Iatrogenic
- Surgery
- Paraspinal injections
39
Q

What are the risk factors for spinal infections?

A 
IV drug use
Endocarditis
Bacteraemia
Degenerative spinal disease/prior spinal surgery
Diabetes
Immunosuppression
40
Q

What are the clinical features of spinal infections?

A

Primary symptom = back/neck pain
Fever variable
Back tenderness/percussion tenderness
Nuchal rigidity variable

41
Q

What are the four clinical stages of a spinal epidural abscess?

A
  1. Back pain and fever
  2. Radicular pain, nuchal rigidity/neck stiffness, and reflex changes
  3. Sensory abnormalities, motor weakness, and bowel and bladder dysfunction
  4. Paralysis
42
Q

What are the causes of spinal infections?

A 
S aureus = most common
Enteric Gram negative bacilli
Pseudomonas aeruginosa
Candida
Groups B and G haemolytic streptococci
Uncommonly
- TB
- Brucellosis
43
Q

What are the investigations for spinal investigations?

A 
MRI for diagnosis and assessment of severity
Attempt at ID of organism
- Blood cultures
- CT guided biopsy
- Open biopsy

MD2 Foundation (42 decks)

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